I think it must be very tricky running a seminar - trying to teach on so many levels simultaneously is difficult. What I have seen some instructors doing is explaining the basic principles, and then going around personally to more experienced students and giving them additional individual tips (sometimes that even seem contrary to what has been said in general).

I tend to look at instructors now in 3 ways - i. those who are teaching me what I know I should be doing, but I can't quite do it, ii. those that are teaching me something that I already know and have now disregarded, and iii. those who are teaching something novel or different which I don't understand (and am usually dubious of).

The 1st category tends to be the routine training we all do, the 2nd category are instructors I just wouldn't seek out, the 3rd category are instructors that may or may not have something to offer but its worth training with (e.g. at seminars) until you can put them into either category 1 or 2.